Question 14 Marks

Anand runs a computer repair service company. For a Lenovo laptop, he charges ₹450 for diagnosis and ₹60 per hour for repairs. For an Acer laptop, he charges ₹360 for diagnosis and ₹90 per hour for repairs.
Q.1. Anand repaired Mr Sharma's Lenovo laptop. He charged ₹810 for the work. How long did he take to complete the repair work?
(a) 5 hours$\quad$(b) 6 hours$\quad$(c) 7 hours$\quad$ (d) 8 hours
Q.2. Anand repaired Mr Singh's Acer laptop. The total charges were ₹1170. How long did he take to complete the repair work?
(a) 9 hours$\quad$(b) 8 hours$\quad$(c) 7 hours$\quad$(d) 6 hours
Q.3. What were the total service charges that Mr Dev had to pay for both the laptops?
(a) ₹ 630 $\quad$(b) ₹810$\quad$ (c) ₹1260$\quad$(d) ₹1620

Answer

1. (b): Suppose Anand spent $x$ hours to repair the Lenovo laptop. Then, $450+60 x=810$
$
\Rightarrow 60 x=810-450 \Rightarrow 60 x=360 \Rightarrow x=\frac{360}{60}=6
$
$\therefore$ he took 6 hours to complete the repair work.
2. (a): Suppose Anand spent $y$ hours to repair the Acer laptop. Then, $360+90 y=1170$
$\Rightarrow 90 y=1170-360 \Rightarrow 90 y=810 \Rightarrow y=\frac{810}{90}=9$.
$\therefore$ he took 9 hours to complete the repair work.
3. (d): Suppose Anand repaired each laptop in $h$ hours.
Then, $450+60 h=360+90 h$
$\Rightarrow 450-360=90 h-60 h \Rightarrow 30 h=90 \Rightarrow h=\frac{90}{30}=3$
$\therefore$ for each laptop, the repair work took 3 hours.
4. (c): For Lenovo laptop, service charges
$=₹(450+60 \times 3)=₹(450+180)=₹ 630 \text {. }$
$\therefore$ service charges for Acer laptop $=₹ 630$.
Total charges for Mr Dev $=₹(630+630)=₹ 1260$.

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